SAN FRANCISCO (KPIX 5) – Every year, it is estimated that 200 people are convicted of shaking babies to death. Doctors have said violent shaking causes babies’ brains to swell and bleed, but now that science looks shaky. KPIX 5 talks to a Bay Area father who was wrongly accused.

The toddler just dropped food on the floor, the pet dog was licking it up, and Kristian Aspelin , with crying baby in arms, ran to the kitchen to find out what was happening. That’s when he fell, dropping 3-month-old Johan onto the floor.

Frantic, Aspelin called 911.

“Johan just went silent from having been crying,” Aspelin remembers, “and I fell into shock.”

And so began Kristian Aspelin’s nightmare. Fifteen hours after his baby was rushed to the emergency room, he was accused of child abuse, of violently shaking his baby, not dropping him.

“The doctors had told us, at least to me, the injuries were inconsistent with my accounts,” Aspelin told KPIX 5.

Baby Johan had bleeding and swelling in the brain and behind his eyes. The symptoms that point to shaken baby syndrome, also known as abusive head trauma. It’s a hypothesis first introduced in 1974, and what pediatricians have been taught to recognize as possible child abuse.

San Francisco police detectives were called in after doctors told the couple Johan was dying.

“Yeah, and they came in and arrested him at the baby’s bedside,” recalled Aspelin’s wife, Jennie. “And Kristian tried to lean over and kiss the baby, and they said, ‘Sir, step away from the baby.’”

Kristian Aspelin was in jail for a week before he could raise enough bail money. He never saw his baby again.

“I broke down, crying,” Kristian Aspelin said when his attorney came to his cell to tell him Johan died.

Aspelin’s attorney Stuart Hanlon found a growing number of doctors who warn that there could be other reasons than just shaking a baby that can cause brain injuries.

“No one says it’s okay to shake your baby,” Hanlon says, “but the question is, could shaking a child cause the type of head injuries that killed him?”

It is a debate that divides the doctors who testify in these shaken baby cases. Pediatricians who see victims of child abuse argue brain bleeding from just a fall is rare, and most likely from abuse.

“The position that shaking can cause these kinds of bleeds have never been substantiated,” Gabaeff argues.

Gabaeff said it is abusive to shake a baby, and it does cause some injury. But shaking alone, he believes, is not enough to cause the bleeding and the brain swelling. He says there are many other causes.

“These things are nonspecific findings that can occur in impact injuries, birth trauma and other complications.” Dr. Gabaeff said “A number of medical problems that can result increased intra-cranial pressure and bleeding around the brain.”

San Francisco prosecutors agreed the evidence of shaken baby syndrome in the Aspelin case was murky, and dropped the murder charges against him.

The American Academy of Pediatrics agrees there could be other medical reasons for the brain swelling and bleeding. But doctors insist that is not always the case, because violent shaking does cause harm.

It is estimated there are about 200 shaking baby convictions a year. The Northern California Innocence Project at Santa Clara University is re-examining some cases helping people who may have been wrongly convicted.

“The danger is people have been convicted on faulty science,” said attorney Paige Kaneb. “It’s science that we now know is wrong. And so how do we deal with that? How many people are in prison based on an incorrect hypothesis that was never proven?”

Kaneb said there have been about a dozen convictions nationwide that have been reversed.

The fallout for the Aspelins was severe. Kristian Aspelin was banned from living with his family while working to prove his innocence, and he had to sell his home to raise money for his defense. He is still bitter over what he called the doctors’ rush to judgment against him.

“One hour after looking at the baby, they decide this is shaken baby, and it took us seven experts and seven months to uncover the truth,” Kristian Aspelin said.

Two and a half years later, the case is over. Aspelin has also won his appeal to get his name off the state child abuse register.

The couple grieves the loss of their baby son. But there is a happy ending of sorts. Just this week, Jennie gave birth to healthy triplets.